1. Field of the Invention
This invention relates to spouts for dispensing liquids from closed containers and more particularly to such spouts that are provided with venting means for admitting air to the closed container.
2. Brief Description of the Prior Art
When liquids are dispensed from closed containers the initial flow of liquid out of the container creates a lower pressure, i.e., a partial vacuum, within the container. If the flow is to continue, the partial vacuum must be relieved by admitting atmospheric air. Otherwise, the pressure difference between the interior of the container and the atmosphere outside the container will slow or stop the dispensing of liquid.
For this reason, containers having dispensing spouts at their lower extremity are often provided with vents at their upper ends to equalize the internal and external pressures as the liquids are dispensed. However, providing separate vents for containers introduces an additional complication into the manufacture of the containers. Furthermore, if the liquid is not all dispensed at one time, it may be necessary to open and close the vent together with the dispensing spout.
Accordingly, a number of dispensing spouts have been designed that incorporate vents to admit atmospheric air to the container when the spout is opened to dispense the liquid.
U.S. Pat. No. 2,790,582, to Halpern, discloses a spout for dispensing liquid from a necked container such as a glass bottle for bottled drinks, salad oil and the like. The spout comprises a cylindrical plug sliding within a sleeve that is fixed in the neck of the bottle. The plug has a sealing shoulder, which closes the vessel when the plug is in its closed position. The spout is provided with an internal passage extending from the interior end of the plug to an aperture on the side thereof that is exposed when the plug is partially withdrawn from the sleeve. An axially extending portion of the cylindrical side of the plug is flattened to provide a breather duct between the plug and the sleeve to admit air when the plug is in the open position. In normal careful pouring, the breather duct is not submerged.
U.S. Pat. No. 3,223,296, to Waddington, discloses a dispensing spout for use at the lower end of large storage containers wherein the spout apparatus is entirely submerged. The spout comprises an external barrel within which an internal barrel can slide and rotate. The barrels are provided with apertures that are in register when the internal barrel is partially withdrawn and rotated. The internal barrel is provided with two internal axial passages, one for liquid and one for air, extending from exterior openings to interior apertures that can be placed in register with apertures in the outer barrel inside the container. One passage allows for flow of liquid from the container to the exterior of the vessel, while the other admits atmospheric air to the interior of the container to equalize the pressure.
Although the prior art devices are effective for their designed applications, they involve certain complications in order to prevent leakage of liquid through the air vents, especially when the spout is first opened.
Accordingly, a need has continued to exist for a liquid dispensing spout of simple structure that provides an air vent that minimizes liquid leakage therethrough and is simple to manufacture and operate.